Image retrieval device and method, photograph time estimation device and method, repetitive structure extraction device and method, and program

1. An image search device comprising: a feature storage unit configured to store image features extracted from a plurality of images which are captured at one or a plurality of locations and which are given different capture times; a temporal feature extraction unit configured to extract a temporal feature according to a predetermined period from an input time; an image feature estimation unit configured to estimate an image feature of an image captured at the input time on a basis of both the temporal feature extracted by the temporal feature extraction unit and a repetitive structure which is used to perform interconversion between components of the image features extracted from the plurality of images and temporal features extracted from capture times of the plurality of images and which is previously learned on a basis of correlations of periodic change between the components of the image features and the temporal features; and a similar feature image search unit configured to search for an image having an image feature similar to the image feature estimated by the image feature estimation unit on a basis of the image feature estimated by the image feature estimation unit and the image features of the plurality of images stored in the feature storage unit.

2. The image search device according to claim 1 , wherein the temporal feature extraction unit is configured to extract the temporal feature including a plurality of variables according to a plurality of different predetermined periods from the input time, and the image feature estimation unit is configured to estimate the image feature of the image captured at the input time on a basis of both the temporal feature extracted by the temporal feature extraction unit and the repetitive structure which is used to perform interconversion between a selected variable of the plurality of variables of the temporal features and components of the image features and which is previously learned on a basis of a correlation of periodic change between the components of the image features and the selected variable of each of the temporal features.

3. An image search method for an image search device including a feature storage unit configured to store image features extracted from a plurality of images which are captured at one or a plurality of locations and which are given different capture times, a temporal feature extraction unit, an image feature estimation unit, and a similar feature image search unit, the image search method comprising: the temporal feature extraction unit extracting a temporal feature according to a predetermined period from an input; the image feature estimation unit estimating an image feature of an image captured at the input time on a basis of both the temporal feature extracted by the temporal feature extraction unit and a repetitive structure which is used to perform interconversion between components of the image features stored in the feature storage unit and temporal features extracted from capture times of the plurality of images and which is previously learned on a basis of correlations of periodic change between the components of the image features and the temporal features; and the similar feature image search unit searching for an image having an image feature similar to the image feature estimated by the image feature estimation unit on a basis of the image feature estimated by the image feature estimation unit and the the image features of the plurality of images stored in the feature storage unit.

4. A non-transitory computer-readable recording medium having a program for causing a computer to function as each unit included in the image search device according to claim 1 .